int interpol(const double *x, const double *fx, int n, 
             double *z, double *pz, int m);

void lsqe(const double *x, const double *y, int n, 
          double *b1, double *b0);

int root(double (*f)(double x), double (*g)(double x), double *x, int *n, 
	 double delta);
